Why is the first ionisation of silicon greater than aluminium?

The simplest answer to this question is that silicon has exactly one more proton than aluminum. As a result, silicon has a greater attraction (effective nuclear charge) for its valence electrons compared to aluminum. read more

The simplest answer to this question is that silicon has exactly one more proton than aluminum. As a result, silicon has a greater attraction (effective nuclear charge) for its valence electrons compared to aluminum. More energy is required to ionize an atom of Si when compared to Al. read more

Aluminum's second ionization energy involves the excitation of a paired, 3s electron. Silicon's second ionization energy involves the excitation of an unpaired, 3p electron. Exciting a paired electron requires more energy than an unpaired paired electron. read more